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Significant rains and cool temperatures

August 21, 2015

Significant rains and cool temperatures:

Last
weekend (Aug 14-16) was the warmest of the summer so far in many parts of the
state with record high temperatures set at some locations (94F at Grand Rapids,
and 93F at Leech Lake Dam and Pokegama Dam). The warmth also brought a
great deal of moist air to the state with dew points climbing into the 70s F in
many areas (some warm minimum temperature records were set as overnight lows
remained in the 70s F).

A slow migrating low pressure system then produced widespread significant
rainfalls across the state over August 16-19. Many observers reported
over 2 inches of rain during this time, and at least a dozen communities
reported over 3 inches. Some single day rainfall records were set at a
number of stations. On August 17th Winnebago received a record
1.18 inches of rain, and Worthington reported a record 1.83 inches. Then
again on August 19th even more observers reported new record
rainfall amounts including:
4.03 inches at Madison (Lac Qui Parle County)
2.91 inches at Wolf Ridge (Lake County)
2.39 inches at Minnesota (Lyon County)
2.15 inches at Dawson (Lac Qui Parle County)
2.02 inches at Marshall (Lyon County)
1.63 inches at Browns Valley (Traverse County)
1.60 inches at Hawley (Clay County)

With the abundant cloud cover and persistent rain, daytime temperatures
remained several degrees below normal, bringing some record cold daytime highs
on August 19th. For most parts of the state afternoon
temperatures remained in the 50s and 60s F. Among those stations setting
new record cold maximum temperatures were:
54F at Orr
55F at Crane Lake, Ely, Grand Marais
56F at Cook
57F at Bemidji, Eveleth, Bigfork, Grand Rapids, Waskish, and Hibbing
58F at Brimson
59F at Baudette, Browns Valley, Moose Lake (tied 1985), and Embarrass
63F at Dodge Center
64F at Windom

All of these highs were on the order of 15-20 degrees F colder than normal.

Fall Season Climate Outlook:

The NOAA Climate Prediction Center issued new seasonal
outlook products on Thursday (Aug 20) of this week. For the period of
September through November the outlook shows equal chances for above or below
normal temperatures across the state and the same for precipitation except that
above normal amounts are slightly favored in southwestern counties. Late
autumn months are favored to show an El Nino signature for temperature which is
reflected in a warmer than normal temperature pattern across Minnesota.

Anniversary year for three significant weather events:

The year 2015 is somewhat uncommon in that it marks an
important anniversary for three significant Minnesota weather events, two of
which many living Minnesota citizens will remember.

The oldest of these events occurred on the afternoon of July 13, 1890. On
that date 125 years ago severe convective thunderstorms and tornadoes came to
eastern Minnesota. A tornado formed in Anoka County and passed across
portions of Ramsey County bringing winds of 160 to 200 mph around 5pm in the
late afternoon. It was especially destructive to Little Canada and Lake
Gervais, killing six people and injuring eleven. The parent thunderstorm
moved southeast bringing destructive wind, hail, and rain to Newport, and then
Frontenac and Maiden Rock along the north end of Lake Pepin. The squall
line winds overturned the excursion boat Sea Wing drowning nearly half
of its 200 passengers, the worst boating disaster in state history. This
story is documented in the Frederick Johnson book The Sea Wing Disaster.

November 11 of this year will mark the 75th anniversary of the
famous Armistice Day Blizzard, still vividly remembered by a number of
Minnesota senior citizens for its ferocity of wind and heavy snow.
November 11, 1940 started out as a mild day, quite suitable for those who
fancied duck hunting. But when a strong storm system approached from the
west the weather took an abrupt turn with the onset of blizzard conditions
including strong winds, declining temperatures and dangerous windchills, low
visibility and heavy snow, at one time accumulating as much as 3 inches per
hour. Snowfalls of 15 to 25 inches blew into 20 foot drifts which blocked
roads and isolated many travelers. Forty-nine Minnesotans lost their
lives in this storm, which was poorly forecasted by the Weather Service.
This story is recounted by many in the book by William Hull called All Hell
Broke Loose: Experiences of Young People During the Armistice Day 1940
Blizzard.

November 10 of this year will mark the 40th Anniversary of the
Sinking of the Edmund Fitzgerald on Lake Superior. November 10,
1975 brought one of the strongest storms to ever cross Lake Superior and the
ore carrier got caught in the teeth of the storm north of Whitefish Bay on the
eastern side. Winds greater than 70 mph produced wave heights of 12 to 15
feet and the ship suddenly sank about 7pm with the loss of all 29 crew
members. This event was immortalized in the Gordon Lightfoot song and
vividly described in a number of books, including Frederick Stonehouse's The
Wreck of the Edmund Fitzgerald.Each year on November 10th Split
Rock Lighthouse hosts “the Edmund Fitzgerald Commemorative Beacon Lightning.”A solemn ceremony is held at 4:30pm on that
date with the ringing of a ship’s bell as the names of the 29 lost crew members
are read.

Weekly Weather Potpourri:

NOAA reports that July of 2015 was globally the warmest month ever reported over the
period from 1880 to 2015 with an average temperature (both land and sea) that
was 1.46°F above the 20th Century mean value. The global
average temperature for the year, January through July is also the highest
measured in the record period.

Though
we were uncomfortably warm last weekend here in the Midwest, we were mild
compared to portions of southwestern Iran last month. NOAA Climate.gov reports
that near Bandar Mahshahr on July 30 about 4:30pm the temperature hit 111°F
with a dew point of 88°F producing a Heat Index Value of 155°F. The next
day about the same time in the afternoon it was 115°F with a dew point of 90°F
and a Heat Index of 165°F.

The European Drought Observatory (EDO) reported this week that portions of Western
Europe are in their worst summer drought since 2003. Many parts of
Germany, France, Hungary, northern Spain and northern Italy are showing
symptoms of drought due to both high temperatures and lack of rainfall
prevailing during the months of June and July. A
recent survey by the Met Office in the United Kingdom finds that 58 percent of
all adults check the weather within an hour of getting up in the morning or
before leaving for work. They further found that women talk about the
weather on a daily basis more than any other topic, more than money,
relationships, or celebrity gossip.

In the Western Pacific Ocean Typhoon Atsani was producing
winds of 115 mph and sea wave heights of 40 to 45 feet. It was expected
to remain well off the southeast coast of Japan and dissipate by the middle of
next week. Further south off the north coast of the Philippines Typhoon
Goni was producing wave heights of 35-40 feet and winds up to 105 mph. It
was bringing heavy rains to the northern Philippines.In the central North Atlantic Hurricane Danny
was migrating westward with peak winds up to 100mph.It may become a threat to Puerto Rico by
early next week.

MPR Listener Question:

I
live in downtown Minneapolis and last weekend my air conditioner broke down, so
I slept out on the balcony, but it was still too warm for sleeping as the
overnight temperatures never dropped below 70F. How many times does this
happen each summer?

Answer:

Residents of the Twin Cities without air conditioning have
to cope with the overnight effects of the urban heat island which keep
nighttime temperatures high. The average number of nights each summer
when it does not cool down below 70F is about 10 in the Twin Cities Metro Area.
This year so far we have recorded 6 such nights. Historically some
summers have brought over 25 nights with temperatures above 70F, including
1936, 1937, and 2013.

Twin Cities Almanac for August 21st:

The average MSP high temperature for this date is 80 degrees F (plus or minus 7 degrees F standard deviation), while the average low is 61 degrees F (plus or minus 6 degrees F standard deviation).

MSP Local Records for August 21st:

MSP weather records for this date include: highest daily maximum temperature of 98 degrees F in 1947; lowest daily maximum temperature of 59 degrees F in 1966: lowest daily minimum temperature is 44 degrees F in 2004; highest daily minimum temperature of 74° F in 1968 and 2013; record precipitation of 3.64 inches 1924; and no snowfall has been recorded on this date.

Average dew point for August 21st is 58 degrees F, with a maximum of 78 degrees F in 1903 and a minimum of 34 degrees F in 2004.

All-time state records for August 21st:

The state record high temperature for this date is 103 degrees F at Moorhead (Clay County) in 1947 and at Milan (Chippewa County) in 1976. The state record low temperature for this date is 23 degrees F at Tower (St Louis County) in 2004. State record precipitation for this date is 6.30 inches at Montevideo (Chippewa County) in 2002; and there has not been any snowfall on this date.

Past Weather Features:

An F-5 (winds over 260 mph) tornado struck Rochester about
5:30 pm on August 21, 1883, killing 37 people and injuring 200. This
tornado also lifted a train off the tracks and tipped it over. Attending
to the injured and rebuilding the city resulted in the formation of the Mayo
Clinic.

August 21st in 1947 and 1976 brought plenty of heat to Minnesota
with widespread readings of 90°F or higher. Many western communities
reached 100°F in the afternoon.

August 21, 2004 brought very cold temperatures to the state. Many
observers reported a morning low in the 30s F. Observers in Hubbard,
Itasca, Cass, and St Louis Counties reported frost with temperature readings in
the 20s F. Ground frost was reported as far south as Mower County.

Outlook:

Rollercoaster ride over the weekend.Sunny and breezy with near normal
temperatures on Saturday and an increasing chance for showers and
thunderstorms. Still breezy with
widespread scattered showers and thunderstorms on Sunday, along with cooler temperatures.
Cooler yet on Monday and Tuesday, then a
warming trend for Wednesday through Friday next week with chances for showers returning
Thursday and Friday.